Greater safety in a small space

(See STOBER at Machine Building North, 13 May 2026, on stand 28)

Developed in collaboration with Pilz, the SX6 combines high safety standards with practical handling.

"We previously equipped two of our 6th generation drive controllers, the SC6 and SI6, with this safety module," says Matthias Meyering, Technical Product Manager at STOBER. "Now it is also available for the new SB6."

The SB6 is a compact stand-alone solution for applications with up to four axes. The series is available in three sizes for low to medium power ranges. It can control both linear and rotary synchronous servo motors, asynchronous motors, and also lean motors. Because the SB6 is especially compact, it fits into control cabinets with installation depths as low as 210 mm.

Extensive safety functions

Equipped with the SX6, the SB6 is suitable for safety-relevant applications up to SIL 3, PL e (category 4) in accordance with DIN 61800-5-2 or DIN EN ISO 13849-1. "The safety module enables the conventional Safe Torque Off (STO), Safe Stop 1 (SS1) and Safe Stop 2 (SS2) stop functions," explains Meyering. It also features Safely-Limited Speed (SLS), Safe Speed Range (SSR), Safe Direction (SDI), Safely-Limited Increment (SLI) and Safe Operating Stop (SOS).

In order to continue increasing the productivity and availability of the machine, STOBER has expanded the monitoring mechanisms of the safety functions beyond basic standardised requirements. Through position-based limit value monitoring and targeted suppression of interference signals, the intended limit values can be approached with a minimal interference distance. The SX6 continuously runs system tests during operation. As a result, cyclical function tests of safety functions that are subject to documentation at the end customer's location are unnecessary - a clear advantage for operational reliability.

"Users benefit from short worst-case response times of less than ten milliseconds, reduced safety distances and rapid restoration of availability," explains Meyering. This significantly increases productivity and system availability." The integrated safety module can intervene in the axis movement immediately and stop the drive in the event of a limit value violation or an emergency stop. Alternatively, it can be configured to only report limit value violations. The successful EtherCAT and FSoE certification also forms the basis for easy integration into EtherCAT-based automation solutions.

Brake management: protection against falling axes

Gravity-loaded axes can inadvertently drop or fall due to mechanical wear or contaminated brakes, endangering people in the hazard area. Meyering explains: "Therefore, the design must incorporate suitable actions to significantly reduce this risk." For this application, STOBER has added a safe brake management system to the SX6.

As a result, the SB6 drive controller with safety module meets German Social Accident Insurance (Deutsche Gesetzliche Unfallversicherung - DGUV) requirements for gravity-loaded axes. "In combination with a motor with a holding brake and the ServoStop motor adapter with an integrated brake, we offer a solution for planning and design in mechanical engineering that is simple and safe at the same time," says Meyering.

The brake management of the SX6 includes the Safe Brake Control (SBC) function, which ensures that the brakes are controlled safely. In addition, the Safe Brake Test (SBT) feature checks the defined braking torque as needed and detects deviations due to factors such as contamination or defects - before the braking torque reaches a critical state. The parameterised inspection interval is also monitored.

Depending on the application or the specifications of the risk assessment, this could be once per production cycle, or every eight hours at the start of a shift, for example. If the holding torque of the brake is no longer sufficient, the "Bed in brake" function is available in the drive controller. The system can then recheck whether the required test torque has been reached again. Since the brake management system supports control of up to two brakes, it covers all the applications specified in the DGUV Division Information Sheet on gravity-loaded axes.